Angiogenic medical cyanoacrylate adhesive

ABSTRACT

Tissue adhesive comprising a cyanoacrylate in combination with an angiogenic factor such as butyric acid or a derivative or a precursor thereof.

The invention relates to adhesives and angiogenesis, in particular theuse of novel angiogenic adhesives in surgery.

Adhesion of tissue is an integral part of all surgical procedures,including closure of skin wounds, reconstruction of nerve ruptures,re-attachment of transplanted tissue, sealing of blood vessels,treatment of pneumothorax and fistulas, support of vascular andintestinal anastomoses, treatment of chondral- and osteochondraldefects, fracture healing, treatment of meniscal tears and rupturedligaments, repair of tendon damage or muscle damage and attachment ofimplanted biomaterials and tissue engineered devices.

The fundamental aim of all tissue adhesives is to hold tissue togetherfor long enough to allow a natural biological repair. Biological repairtypically involves the activation of cells in the tissue to a repairmode and, critically, the stimulation of angiogenesis to provide repaircells, nutrition and oxygen to the activated cells.

There is extensive literature describing the use of bioactives tostimulate tissue repair. However, stimulation of tissue repairmechanisms alone, such as angiogenesis, using biological actives willnot be enough to heal a large defect between tissues. It is essentialthat the two tissues to be integrated are held in close apposition atthe macroscopic level in order to allow the biological mechanisms tobond the tissue at the microscopic level.

To date tissue adhesion is mainly done using mechanical fasteningtechniques such as suturing or stapling. There are occasions, however,when the application of a biological glue or adhesive would bebeneficial. For example, sutures are inappropriate for cartilage repairas these cause non-healing defects to form in the cartilage where theyare placed. Suturing of internal tissue and organs is also slow andtechnically difficult compared to application of an adhesive. Othertissues that may require adhesion such as bone or certain implants maybe too hard for sutures or staples whilst other soft tissues may be toofragile for the suture or staple to hold under tension.

Consequently, adhesives have been developed for biological applications,including biological adhesives such as fibrin and synthetic adhesivessuch as cyanoacrylates.

Biological adhesives that utilise naturally occurring adhesive processessuch as the blood coagulation cascade (fibrin) have a number ofadvantages. They are readily accepted by the body and break downcompletely to allow a full biological repair. However, the bondingstrength of such adhesives is well below the levels required for manyapplications, including all those where the bonded tissue is under anysignificant tension.

A number of synthetic adhesives have been manufactured for industrialand consumer use. Some of these, including cyanoacrylates, have beenused to glue biological tissues.

The advantage of using cyanoacrylates is that they form an extremelystrong bond between tissues. However, they have not replaced the use ofother fixation devices because the cyanoacrylate acts as a barrier tobiological repair.

It would therefore be desirable to produce a cyanoacrylate adhesive thatactively stimulated tissue repair.

It is a well established fact that, in most tissues, stimulation ofangiogenesis results in the acceleration of tissue repair whilstinhibition of angiogenesis can result in ischaemia and tissue death.

There is published literature on the delivery of angiogenic factors tostimulate tissue repair. WO 97/16176, WO 01/03607 and U.S. Pat. No.6,152,141 describe the release of angiogenic facors to accelerate bloodvessel repair, EP 0,295,721 describes the promotion of meniscal healingwith angiogenic factors, whilst EP 0,530,804 describes the use ofangiogenic materials to promote cartilage and bone healing. However,none of these prior art teach the incorporation of angiogenic factorsinto cyanoacrylate adhesives.

Butyric acid is a potent angiogenic agent and has been used as anangiogenic factor for the treatment of burns, wounds and bone fractures.Butryic acid, also known as butanoic acid, is a four carbon fatty acid.The literature suggest that the local release of 10-1000 ng of butyricacid is sufficient to achieve the desired angiogenic effect. However,butyric acid is known to be removed rapidly from the body and thereforefor therapeutic angiogenic applications it has been suggested that it beincorporated into a sustained release delivery vehicle. A lipidangiogenic factor has been isolated from omentum (Catsimpoolas et al.,1984, JAMA 252:2034-2036). The angiogenic factor was found to bemonobutyrin (Wilkinson et al., 1991, J. Biol. Chem. 266:16886-16891).

Monobutyrin can be considered to be a prodrug of butyric acid. Otherprodrugs include tributyrin. Tributyrin can be hydrolysed to releasebutyric acid (Chen et al, 1994, Cancer Research 54, 3494-3499, Bohmig etal, 1999, Transplant Immunology, 7, 221-227). Tributyrin has beenproposed for use in anti-cancer therapies where it is desirable toinhibit angiogenesis, it has not been considered has an angiogenic drug.

There is prior art describing the use of cyanoacrylate adhesives intissue repair applications (Barley et al., U.S. Pat. No. 6,342,213,methods for treating non-suturable wounds by use of cyanoacrylateadhesives; Hyon et al., U.S. Pat. No. 6,316,523, adhesive compositionfor surgical use; Shalaby, U.S. Pat. No. 6,299,631,polyester/cyanoacrylate tissue adhesive formulations; Kotzev, U.S. Pat.No. 6,224,622, bioabsorable cyanoacrylate tissue adhesives). However,none of these patents disclose the addition of an angiogenic componentto the cyanoacrylate.

There is literature describing the incorporation of active moleculesinto tissue sealants (MacPhee et al., U.S. Pat. No. 6,117,425,Supplemented and unsupplemented tissue sealants, method of theirproduction and use), but this patent makes no mention of cyanoacrylates,despite providing long lists of other frequently used tissue sealants.

Simple active molecules such as Iodine have been incorporated intocyanoacrylates (Askill et al., U.S. Pat. No. 6,214,332, methods forclosing suturable wounds by use of cyanoacrylate ester compositionscomprising an antimicrobial agent), but angiogenic agents are usuallyproteins or chemically active nucleophiles that will cure thecyanoacrylate prematurely, rendering it useless as a tissue adhesive.Thus there is prejudice in the art that suggests that it would not bepossible to incorporate an angiogenic agent into a cyanoacrylate.

It is an objective of the present invention to provide a cyanoacrylateadhesive for use in biological applications that releases a biologicallyactive angiogenic agent.

We have discovered that tributyrin and some related molecules (butyricacid prodrugs), which are also capable of stimulating angiogenesis,surprisingly do not cause cyanoacrylate to prematurely cure.

Accordingly, to the present invention there is provided a tissueadhesive comprising a cyanoacrylate in combination with an angiogenicfactor, which is releasable in amounts that will cause a pharmacologicaleffect.

The cyanoacrylate adhesive will typically be selected from the groupconsisting of alkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate,alkoxyalkyl 2-cyanoacrylate, and carbalkoxyalkyl 2-cyanoacrylate,wherein the alkyl group of said one or more cyanoacrylates has 1 to 16carbon atoms.

The cyanoacrylate will preferably be selected from the group consistingof methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, n-propyl2-cyanoacrylate, iso-propyl 2-cyanoacrylate, n-butyl 2-cyanoacrylate,iso-butyl 2-cyanoacrylate, hexyl 2-cyanoacrylate, n-octyl2-cyanoacrylate, 2-octyl 2-cyanoacrylate, 2-methoxyethyl2-cyanoacrylate, 2-ethoxyethyl 2-cyanoacrylate and 2-propoxyethyl2-cyanoacrylate.

In a first embodiment of this invention the angiogenic factor is butyricacid or a derivative or precursor thereof.

The angiogenic factors may include:

-   -   Butyric acid (butanoic acid, C₄H₈O₂) and butyric acid salts,        including sodium, potassium, calcium, ammonium and lithium salts    -   Butyric acid derivatives and polymers containing butyric acid        residues    -   α-monobutyrin (1-glycerol butyrate; 1-(2,3        dihydroxypropylbutanoate; C₇H₁₄O₄)    -   α-dibutyrin (1,3-glyceroldibutyrate; 1,3-(2        hydroxypropyl)dibutanoate; C₁₁H₂₀O₅)    -   β-dibutyrin (1,3-glyceroldibutyrate; 1,2-(3        hydroxypropyl)dibutanoate; C₁₁H₂₀O₅)    -   tributyrin (glcerol tributyrate; 1,2,3-(propyl)tributanoate;        C₁₅H₂₆O₆)    -   hydroxybutyrate and polymers containing hydroxybutyric acid        residues

The angiogenic factor is added to the cyanoacrylate in such proportionsas to result in an adhesive strength, aptly of not less than 0.05 Mpa,preferably at least 0.2 MPa and more preferably at least 0.5 Mpa.Typically the resultant adhesive strength should range from 0.05 to 0.8Mpa.

Once cured, the cyanoacrylate will aptly release at least 1 ng/mladhesive of the angiogenic factor. Suitably the cyanoacrylate willrelease less than 100 μg of angiogenic factor, although preferably itwill release less than 10 μg and more preferably less than 1 μg of theangiogenic factor.

The invention will be illustrated by references to the followingexamples and the accompanying drawings in which FIG. 1 shows that 5% to50% (w/w) tributyrin can be added to cyanoacrylate without anunacceptable loss of adhesive property.

FIG. 2 shows that tributyrin is released from a 5% w/w tributyrincyanoacrylate sample over a 7 day period.

EXAMPLE 1

0.5 g of the sterile tributyrin was added to cyanoacrylate (9.5 g) toproduce a 5% (w/w) blend in a sterile plastic universal tube. This wasmixed for 2 minutes to ensure a homogenous blend. 40 μl aliquots of theblended adhesive were applied to freshly cut surfaces of costalcartilage. The two surfaces were held together for 1 minute allowingfixation and curing was allowed to continue for an additional hour inaqueous conditions. The bond strength was tested using a Nene MC3000machine, where the applied force required to separate the bonded piecesof cartilage was recorded. The data showed that 5% to 50% (w/w)tributyrin can be added to cyanoacrylate without an unacceptable loss ofadhesive property.

EXAMPLE 2

0.5g of the sterile tributyrin was added to cyanoacrylate (9.5 g) toproduce a 5% (w/w) blend in a sterile plastic universal tube. This wasmixed for 2 minutes to ensure a homogenous blend. Small disks of theblended adhesive were cast onto a basic solution (dilute triethylamine0.1% aq). The disks were removed, washed briefly and dried. The diskswere then placed into 2 ml water and stored at 50° C. for 1, 5 or 7 dayswith continuous agitation. The water was removed then added to 2 mlsdichloromethane in order to extract any released tributyrin. Thedichloromethane layer was analysed using gas chromatography and theamount of tributyrin recorded. The disks were dried and then placed intofresh water at 50° C. for an additional day. The amount of tributyrinreleased into the fresh water was measured as described for the firstsamples. The data showed that tributyrin is released from a 5% w/wtributyrin cyanoacrylate sample over a 7 day period.

1. A tissue adhesive comprising a cyanoacrylate in combination with anangiogenic factor.
 2. A tissue adhesive according to claim 1 wherein theangiogenic factor is butyric acid or a derivative or precursor thereof.3. A tissue adhesive according to claim 2 wherein the angiogenic factoris a butyric acid salt.
 4. A tissue adhesive according to claim 3wherein the angiogenic factor is a sodium, potassium, calcium, ammoniumor lithium butyric acid salt.
 5. A tissue adhesive according to claim 2wherein the butyric acid, derivative or precursor thereof is present asa polymer containing residues of butyric acid or hydroxybutyric acid. 6.A tissue adhesive according to claim 1 wherein the angiogenic factor isα-monobutyrin, α-dibutyrin, β-dibutyrin or tributyrin.
 7. A tissueadhesive according to claim 1 wherein the angiogenic factor ishydroxybutyrate.
 8. A tissue adhesive according to claim 1 wherein thecyanoacrylate is selected from the following group: alkyl2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate,or carbalkoxyalkyl 2-cyanoacrylate.
 9. A tissue adhesive according toclaim 8 wherein the alkyl group of said cyanoacrylates has 1 to 16carbon atoms.
 10. A tissue adhesive according to claim 1 wherein thecyanoacrylate is selected from the following group: methyl2-cyanoacrylate, ethyl 2-cyanoacrylate, n-propyl 2-cyanoacrylate,iso-propyl 2-cyanoacrylate, n-butyl 2-cyanoacrylate, iso-butyl2-cyanoacrylate, hexyl 2-cyanoacrylate, n-octyl 2-cyanoacrylate, 2-octyl2-cyanoacrylate, 2-methoxyethyl 2-cyanoacrylate, 2-ethoxyethyl2-cyanoacrylate, and 2-propoxyethyl 2-cyanoacrylate.
 11. A tissueadhesive according to claim 1 that has an adhesive strength of at least0.05 Mpa.
 12. A tissue adhesive according to claim 1 that has anadhesive strength of between 0.05 and 0.8 Mpa.
 13. A tissue adhesiveaccording to claim 1 that releases at least 1 ng/ml adhesive of theangiogenic factor.
 14. A tissue adhesive according to claim 1 thatreleases at least 10 ng of the angiogenic factor.
 15. A tissue adhesiveaccording to claim 1 that releases less than 10 μg of the angiogenicfactor.
 16. A tissue adhesive according to claim 1 that releases lessthan 1 μg of the angiogenic factor.
 17. A tissue adhesive according toclaim 1 that contains at least 5% w/w of angiogenic factor.